4-fluorophenethylamine, 4-(trifluoromethoxy)-phenethylamine and other fluorine-containing phenethylamines are intermediates for preparing agrochemicals. J. Am. Chem. Soc. 63, 602 (1941) discloses that 4-fluorophenethylamine can be prepared in a multi-step process. This process gives, starting from p-fluorophenylmagnesium bromide, by addition of ethylene oxide with subsequent hydrolysis, p-fluorophenethyl alcohol which is converted with phosphorus tribromide into p-fluoro. Disadvantageous for using this process on an industrial scale are the high expenditure required for carrying out a Grignard reaction and the multi-step synthesis.
In another process for preparing 4-fluorophenethylamine (see J. Org. Chem. 23, 1979 (1958)), p-fluorobenzylchloride is used as starting material, which is reacted with sodium cyanide to give p-fluorophenylacetonitrile which is then finally reduced using sodium aluminium hydride or lithium aluminium hydride. This process has the disadvantages that some of the required benzyl chlorides are difficult to prepare, and that the handling of sodium aluminium hydride or lithium aluminium hydride requires great safety precautions. Thus, this process is likewise unsuitable for industrial application.
There is therefore still a demand for a process which allows the preparation of fluorine-containing phenethylamines in a simple manner, from easily obtainable starting materials and without any high technical expenditure.